Oil cooler



FIG. 1 is a front elevational view of an oil cooler, showing my new design;

FIG. 2 is a top view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a bottom view thereof. 

I claim the ornamental design for an oil cooler, as shown. 